196 O. jS. Prosser — Names for the formations 



In the report which followed, Dr. Newberry gave a detailed 

 account of the Carboniferous system of Ohio as then known, 

 and to the list of formations of the former section he added 

 the Upper Barren Measures with a thickness of 300 feet (?) and 

 continued the numbering of the principal coal seams as far as 

 13 inclusive, of which No. 1 indicated the lowest coal* In 

 this classification, however, the base of the Lower Coal-meas- 

 ures was carried considerably lower than in Pennsylvania, so 

 that the division contained a considerable part of Rogers' Serai 

 Conglomerate, Coals Nos. 1, 2 and 3 belonging in the Con- 

 glomerate. 



In 1884 the volume on Economic Geology appeared, contain- 

 ing Dr. Orton's exhaustive account of the Lower Coal-measures 

 of Ohio. The classification of Rogers is quoted and explained, f 

 but the greater part of the Conglomerate was included in the 

 Lower Coal-measures, since this formation began with the 

 lowest coal seam, as was the case in the earlier classification of 

 Newberry. Dr. Orton stated that '" In point of fact, there is 

 no more marked separation between the highest coal seam of 

 the Conglomerate series and the lowest of the Productive 

 Measures than can be found between two coals of the latter 

 subdivision.'^ It was shown, however, that Coal No. 4 of 

 Newberry, occurring just below the Pntnam Hill limestone, was 

 probably equivalent to the Brookville Coal of Pennsylvania, 

 which in that state occurs at about the base of the Lower Pro- 

 ductive Measures or Allegheny formation. § 



In 1888 the complete Rogers' classification of Pennsylvania, 

 however, was adopted, as is shown in the following table : 



" Upper Barren Coal Measures 500 feet 



Upper Productive Coal Measures 200 feet 



Lower Barren Coal Measures 500 feet 



Lower Productive Coal Measures 250 feet 



Conglomerate Group 250 feet "|| 



Regarding the change in the classification for the two lower 

 divisions from that of the preceding report, is the following 

 explanation : " In the review in Vol. V, the Conglomerate 

 series of Pennsylvania was included with the Lower Coal 

 Measures, though the boundaries of each were shown to be 

 clearly recognizable here. There are, however, less imperative 

 grounds for the separation in Ohio than in Pennsylvania and 



* Rept. Geol. Surv. Ohio, vol. ii, pt. i, 1874, "Section of the Carboniferous 

 rocks of Ohio," facing p. 81. 



•f-Rept. Geol. Surv., vol. v, pp. 1, 2. 



i Ibid., p. 10. §Ibid., pp. 160, 230. 



j| Ibid.., vol. vi, p. 3; see also "Vertical section of the rocks of Ohio," facing 

 p. 4. 



